Toward the end of pregnancy, your clinician will likely tell you it’s time to test for group B strep. It is a standard of prenatal care, and the results are important to best protect your baby from significant and dangerous illnesses.

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Dr. Ankita Langan

We talked to Dr. Ankita Langan with Novant Health Queen City OB/GYN in Charlotte to answer common questions women might have.

What is group B strep?

Group B strep is a type of bacteria that naturally colonizes or lives on the skin or genital tract of some women. In most cases, it is a harmless bacteria that does not pose a risk to women who test positive for it. In some rare scenarios, it can cause a minor infection like a urinary tract infection, or UTI.

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When are pregnant women tested for it and why?

You’ll be tested for group B strep at 35 to 37 weeks. The test is painless; a quick swab of the skin around the vaginal and rectal area. Colonization of bacteria anywhere in our bodies is always in flux, and the types of bacteria and amount of it can shift throughout our lifetime. Testing is done late in pregnancy to give an accurate and timely reading, informing providers that antibiotics might need to be given during delivery. Medication will protect the baby from becoming infected with group B strep, which can cause significant illnesses that could be life-threatening or lead to long-term impacts.

What happens if I test positive?

Between 25% to 30% of women will test positive for group B strep. If you test do, there’s no need to change your lifestyle or how you are managing your pregnancy. There is not much you can do to be proactive; it will be noted in your chart, and you will be given ampicillin, an IV antibiotic during labor and delivery. That treatment is re-dosed every six hours throughout the course of labor, so the newborn is protected.

If you are compliant with prenatal care and give birth in a hospital, the chance of passing an infection to your baby should be very low. Home births would be advised against for women who test positive because the antibiotic that is used to treat group B strep is given through an IV and would not be available in that setting.


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What is the risk to babies?

Unlike the minimal risk to women who test positive, a group B strep infection can be serious in a newborn. Infected babies can develop serious illnesses like meningitis, pneumonia or sepsis. Any of those can be life-threatening or have long-term impacts on a baby.

The bacteria will not cause any harm to your baby while they are in utero, as exposure only happens in the birth canal. Your baby will not necessarily be tested for group B strep simply because you tested positive, but out of an abundance of caution, the pediatric team will monitor the baby for fever or signs of meningitis or pneumonia.

Does a cesarean section eliminate the risk?

Even if you are scheduled for a C-section, you’ll still be tested for group B strep around 35 to 37 weeks in case your water breaks, or you start labor before being admitted to the hospital. If that barrier is broken there is some risk of transmission, so the delivery team will need to know if monitoring or testing the baby is necessary.

Providers would not recommend a C-section simply because you test positive for group B strep. That’s because if you are on IV antibiotics during delivery, the risk of transmission is so low.

What if I go into labor before getting my group B strep test?

If your group B strep status is unknown and you go into labor early, you will be treated with the antibiotics out of an abundance of caution. Getting the antibiotic regardless of your status does not cause any harm.